Carburetor nozzle



Oct. 14, 1969 F- J. MARSEE E L CARBURETOR NOZ ZLE Filed May 19, 1966 United States Patent 3,472,495 CARBURETOR NOZZLE Frederick J. Marsee, Detroit, and Lamont Eltinge,

Birmingham, Mich., assignors to Ethyl Corporation,

New York, N.Y., a corporation of Virginia Filed May 19, 1966, Ser. No. 551,444 Int. 'Cl. F02m 37/00 US. Cl. 261-76 11 Claims ABSTRACT OF THE DISCLOSURE Fuel discharge nozzle for downdraft carburetor is arranged to flow discharging fuel around top of fr'ustoconical skirt held in carburetor throat and having walls flaring outwardly in downward direction. Fuel flows from under a protecting cover down over those Walls where it is exposed to air flow, and is torn off in droplets at lower edge of walls. Walls can have steps to provide more such edges, and fuel can be blocked from flowing over part of skirt to improve uniformity of mixture supplied to different cylinders of an engine.

In the interest of economy as well as the reduction of undesired emissions from the exhaust of a gasoline engine, it is desirable to operate the engine with relatively lean fuel mixtures. In any practical multi-cylinder engine the mixture ratios provided by the carburetor system may differ widely from cylinder to cylinder and this variation is much greater during engine Warmup. Since the leanest cylinder must receive an ignitable mixture during warmup, the mixture supplied by the carburetor can be richer by several ratios than the leanest mixture usable in the engine when it is hot.

It is an object of the present invention to provide a carburetor nozzle which discharges fuel into the throat of a carburetor in a highly satisfactory and efficient manner and enables better operation of multi-cylinder engines with relatively lean fuel mixtures.

In accordance with the present invention a carburetor nozzle having a generally horizontally extending annular discharge portion is provided for discharging fuel into the throat of a carburetor. The nozzle includes a generally conical skirt below the discharge portion which skirt flares outwardly in the downward direction so that the discharged fuel flows over the exterior of the skirt and is blown off in small droplets by air moving through the throat. The nozzle provides for high shear of the fuel by the air flowing over the fuelwetted skirt and leads to better atomization. Turbulence in the area of the skirt also aids in mixing the fuel and air, and can be increased by forming steps or other irregularities on the skirt.

The discharge portion of the nozzle may be partially blocked so that fuel is discharged over the skirt only through the unblocked section of the discharge portion.

The foregoing as well as additional features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description of preferred embodiments in conjunction with the accompanying drawings in which:

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention;

FIG. 2 is a sectional view on line 22 of FIG. 1;

FIG. 3 is a cross-sectional view similar to FIG. 1, of another embodiment of the present invention; and

FIG. 4 is a further cross-sectional view similar to FIGS. 1 and 3, of still another embodiment of the present invention.

Referring in more particularity to the drawings, numeral represents a carburetor having air horn 12 and a throttle plate 14 suitably journaled in the throttle bore ice 15 for movement between open and closed positions. The carburetor includes a fuel source 16 connected to the carburetor throat 17 by a line 18.

A nozzle 20 having a generally horizontally extending annular portion 22 fed by line 18, is provided for discharging fuel into the carburetor throat. The nozzle includes a generally frusto conical skirt 24 below the discharge portion 22 and connected to a stem 26 around which the discharge portion is formed. The skirt 24 flares outwardly in the downward direction and can be provided with a series of external annular steps 28. The discharge portion 22 has a cover 30 arranged so that air flowing through the carburetor throat in a downward direction does not impinge upon the discharged fuel until the fuel leaves the discharge portion 22 of the nozzle.

The nozzle 20 may also include a barrier 32 which blocks the annular discharge portion 22 at one or more locations so that fuel is discharged only through the unblocked section 34 of the discharge portion 22. The unblocked section may for example extend approximately three-fourths of the way around the nozzle.

In operation, fuel is sucked into the carburetor throat from the source 16 through the line 18 as by suction developed at venturi 17. The fuel is then discharged through the unblocked section of the discharge portion 22 and flows over the external annular steps 28 of the conical skirt 24. These steps provide edges from which liquid fuel is torn off in very small droplets by the air moving through the throat. In addition the steps create a turbulent flow of the air where it tears off the droplets. This makes for even higher shear of the fuel by the air and leads to more eflicient atomization of the fuel, and further reduces the drop sizes of the fuel. The resulting fuel-air mixtures are more uniformly distributed to the cylinders of multi-cylinder engines.

Where an engine has an intake manifold with a poor mixture distribution pattern, i.e. one which is not uniform to all the cylinders, barrier 32 of the discharge portion 22 may be adjusted to compensate for the non-uniformity. By increasing or decreasing the size of the barrier 32 or by orienting it with respect to the discharge portion, it will reduce the amount of fuel delivered to any desired location :or locations of the manifold. This can lean down the relatively rich portions of the pattern so that a closer approach to uniform fuel distribution is obtained.

FIG. 3 illustrates another nozzle 40- which may be substantially similar to nozzle 20 of FIG. 1, with a generally conical skirt 42 whose exterior 44 is relatively smooth. In use, the nozzle 40 discharges fuel into the carburetor throat through annular discharge portion 22 in the same manner as the nozzle 20. The discharged fuel is atomized by air moving through the throat as the fuel flows over the fuel-wetted smooth exterior 44 of the skirt. The discharge portion of the nozzle 40 may include a blocked section which functions to uniformly distribute the fuel in the same manner as explained above in conjunction with the embodiment illustrated in FIG. 1.

Another nozzle embodiment 60 of the present invention is illustrated in FIG. 4. Nozzle 60 includes a conical skirt 62 which flares outwardly in the downward direction and has a pair of annular external steps 64. Fuel discharged into the throat of the carburetor flows over the skirt in the same manner as the other embodiments and is blown off in small droplets by air moving through the throat. The steps provide for even higher shear of the fuel by the air and lead to better atomization. Unlike the previous embodiments, nozzle 60 does not include a blocked discharge section and fuel is therefore discharged through the complete annular discharge portion.

The actual flare of the nozzle skirts need only be enough to expose to the moving air the fuel flowing over it. This flare can be as little as degrees from the vertical, and can be as much as 45 degrees from the vertical. The lowest edge of the skirt can be from about oneeighth to about one-half the diameter of throat 17 although other sizes are equally suitable. It is preferred that the nozzle be hollow inasmuch as this provides less obstruction of the flow of air through the throat. The improved mixtures formed from the foregoing nozzles can be leaner than 14.5 to 1 and as lean as 15.5 to 1 or even leaner for cruise operation of an automobile powered by an engine having such a nozzle. These nozzles can be used in pairs for dual barrel carburetors and can also be used to provide idle operating mixtures according to the arrangements described in copending application Ser. No. 443,956 filed Mar. 30, 1965, now US. Patent 3,310,- 045 granted Mar. 21, 1967.

What is claimed is:

1. A carburetor nozzle having a generally horizontally extending substantially annular discharge portion for discharging fuel into the throat of a carburetor, and a generally conical skirt below the discharge portion, said skirt flaring outwardly in the downward direction and including a series of external annular steps so that the discharged fuel flows over the steps down the exterior of the skirt over the entire extent of the discharge portion and is blown off in small droplets by air moving through the throat.

2. A nozzle as in claim 1 wherein said discharge portion includes a cover section arranged so that the air flowing through the carburetor throat does not impinge upon the discharged fuel until it flows over the skirt.

3. A nozzle as in claim 1 in which the interior of the skirt opens in generally unrestricted manner through the top and bottom of the nozzle so that air can freely move downward through the interior of the nozzle.

4. A nozzle as in claim 1 wherein the discharge portion does not extend completely around the skirt so that the discharge of fuel over the skirt is correspondingly incomplete.

5. A nozzle as in claim 4 wherein the discharge portion extends approximately three-fourths of the way around the skirt.

6. A carburetor having a venturi in the low pressure region of which is positioned a fuel discharging nozzle that includes a generally horizontal substantially annular downwardly directed discharge portion connected to discharge unatomized fuel and below which the nozzle has an exposed skirt that flares outwardly in the downward direction and has at least a lower edge, so that throughout the extent of the discharge portion the supplied fuel flows down over the exterior of the skirt and is blown off the skirt in small droplets by air moving through the venturi.

7. A carburetor as in claim 6 in which the skirt has a diameter A; to /2 the diameter of the throat of the venturi and the interior of the skirt opens through the top and bottom of the nozzle in essentially unobstructed manner so that air can freely move downwardly through the interior of the nozzle.

8. A carburetor as in claim 7 in which the discharge portion of the nozzle is covered so that the air flowing through the throat does not impinge on the supplied fuel until that fuel flows over the skirt.

9. A carburetor nozzle having a generally horizontally extending substantially annular downwardly directed discharge portion connected to discharge unatomized fuel in the throat of a carburetor, and a generally conical exposed skirt below the discharge portion, the skirt flaring outwardly in the downward direction so that the discharged fuel flows over the exterior of the skirt and is blown off in small droplets by air moving through the throat, and the skirt having a hollow interior opening through the top and bottom of the nozzle in essentially unobstructed manner so that air can move freely through the interior of the nozzle.

10. A nozzle as in claim 9 in which the discharge portion is covered so that air flowing through the throat does not impinge on the fuel until the fuel flows over the skirt.

11. A carburetor nozzle having a generally horizontally extending substantially annular downwardly directed discharge portion connected to discharge unatomized fuel in the throat of a carburetor, and a generally conical exposed skirt below the discharge portion, the skirt flaring outwardly in the downward direction so that the discharged fuel flows over the exterior of the skirt and is blown off in small droplets by air moving through the throat, and the discharge portion extends about threefourths of the way around the skirt.

References Cited UNITED STATES PATENTS 2,102,800 12/1937 Killrneyer et al. 26176 X 2,726,073 12/1955 Seld 26176 X 1,630,410 5/ 1927 Stevenson. 2,092,015 9/1937 Pierce. 2,376,298 5/ 1945 Welp. 2,704,659 3/ 1955 Fuchs. 2,821,373 1/1958 Olson 26l78 3,085,793 4/1963 Pike et al. 3,326,539 6/1967 Phipps 261-78 XR FOREIGN PATENTS 532,832 11/1921 France. 935,034 11/1955 Germany.

OTHER REFERENCES Beck, German printed application No. 1,043,712, November 1958.

TIM R. MILES, Primary Examiner US. Cl. X.R. 

